Many major energy companies already face a talent gap in their workforce, and an impending wave of retiring CEOs could further burden the businesses amid the shale boom.

Almost 60 percent of the 100 largest public energy companies in Houston are led by CEOs 55 or older, according to research by the Houston Business Journal, and might be looking for their next top notch executive.

Of the 67 energy companies on HBJ’s 2013 list of the top 100 public companies, 16 of them — 24.9 percent — are older than 60. The average age of retirement in the U.S. is 61, according to Gallup’s 2013 Economy and Personal Finance survey.

Across the industry, about 30 percent of oil and gas executives are expected to retire by 2016, said David Percival, CEO of executive energy talent firm Spencer Ogden, based in London.

“Perhaps there is some need for fresh blood in the ranks,” he said.

The problem, though, is the so-called “great crew change” that’s happening on the heels of a period in which energy companies didn’t invest in talent.

At Houston’s Apache Corp. (NYSE: APA), long-time CEO G. Steven Farris is 65. While there’s been no official word on Farris’ potential retirement plans, analyst Mark Hanson at Morningstar Inc. in Chicago said that it would seem natural for a company led by a 65-year-old to consider building some strength on its bench. Farris joined Apache’s board of directors in 1994, and has served as CEO since May 2002.

“It’s hard to gauge, though,” Hanson said. “He’s been at the helm for so long.”

A recent national survey of oil and gas executives found that more than 90 percent of companies had movement among senior officers during the last two years.

“The energy industry is facing an imminent shortage of executive talent as well as a lack of employees with the required competencies these companies need to compete in the global marketplace,” said John Lamar, managing director and chief of the energy practice at The Alexander Group, an executive search firm in Houston.

In fact, Lamar’s research found it was the CEO role that showed the highest turnover rate at 28.9 percent, followed by COOs and division or regional executives.

Among CEOs in the energy field, the reasons for the vacancies vary. At Parker Drilling Co. (NYSE: PKD) in Houston, the chief spot opened when then-CEO David Mannon left to pursue other interests. He has since resurfaced as managing director of Broadreach Advisors in Houston, an upstream energy consulting firm. Gary Rich has been CEO at Parker for almost a year.

In some cases, the departures are a response to the urges of shareholders or board members. At Lucas Energy Inc. (NYSE: LEI) in Houston, the board of directors decided they wanted to take a different path at the end of 2012, and founder and CEO William Sawyer resigned. Anthony Schnur has been on the job in the chief executive role since January.

In the midst of an energy renaissance, shareholders have high expectations from their executive leadership, Percival said.

“As CEO, their task is to increase shareholder value. One of the reasons they are getting moved quite swiftly and at a fair volume is that shareholders don’t think they’re returning the value they should in the middle of a shale boom,” he said. “That’s probably driving this, too. There are some mean shareholders, and some are looking for high returns. That’s an awful lot of pressure.”

When Schnur was named CEO of Lucas in December, the company hadn’t seen a profit in years and it was mired in legal troubles.

In April, Schnur, along with CFO William Dale, managed to settle a $22 million lawsuit with Nordic Oil USA 1 LLLP in Las Vegas over the termination of a purchase agreement. Lucas agreed to pay Nordic $1.1 million and assign less than 5 percent of its current production to Nordic.

The settlement did more than relieve a legal burden, Schnur said at the time.

“We have established a clear path to remove the uncertainty and the related approximately $24 million in obligations from our balance sheet,” he said.

Inside of six months, Schnur has managed to undo what it took several years for Lucas to accomplish: He cut a swollen staff by 40 percent, settled millions of dollars in the legal dispute, and put the company on a path to profit.

“We’re out of ICU,” Schnur said. “Now, we’re in the exciting phase.”

Recent moves

At the age of 62, Marathon Oil Corp. (NYSE: MRO) CEO Clarence Cazalot Jr. was just a few years away from the mandatory retirement age at the Houston exploration and production company when he announced his retirement plan. He’s been replaced by Lee Tillman, the 51-year-old former Exxon Mobil Corp. (NYSE: XOM) executive, who debuted in the post in July.

Also in July, Mark Papa retired from the CEO role of EOG Resources Inc. (NYSE: EOG) at 66, after leading the company for 13 years. Bill Thomas, 60, has taken up the helm.

Top of the game

Rich Kinder of Kinder Morgan Inc. (NYSE: KMI) in Houston is the oldest CEO of an energy company on Houston Business Journal’s list of the city’s top 100 public companies. But, just because at 68 he’s past the nation’s average age of retirement, it’s not expected he’ll begin taking a more leisurely pace anytime soon.

In fact, it’s more likely he’ll follow the example set by the late Houston energy mogul, Dan Duncan, said Kenny Feng, president and CEO of The Alerian Index in Dallas.

Duncan was, like Kinder, a multibillionaire in the energy master limited partnership space, chairman of the board at Houston’s Enterprise Products Partners LP (NYSE: EPD). He was still plugging away full time when he died at the age of 77.

“(Kinder) famously receives a $1 salary each year, knowing full well that the value of quarterly dividends and distributions from the various Kinder entities meaningfully dwarfs any potential compensation of the traditional salary-bonus-options variety,” Feng said. “All this to say, he’s probably doing it for the legacy, not the money.”

The shale gale

As hydraulic fracturing has set the stage for increasing exploration and development, it’s also created a hiring frenzy in the field. During the second quarter of 2013, Texas landed 2,400 jobs in the oil and gas industry. Nationwide, almost 150,000 energy jobs have been added since 2010, according to research by Rigzone, a Houston-based online oil and gas information, data and talent recruitment resource.

How much does it cost a company when the CEO leaves?

Executive exit packages vary and can become complicated, especially at the CEO level, recruiters say, but one in 2011 raised so much shareholder ire that the departing CEO eventually agreed to forego a $100 million payday.

As part of his employment contract, former Nabors Industries Ltd.’s (NYSE: NBR) Chief Executive Eugene Isenberg was due to receive the payment when he was replaced as CEO and named chairman. Analysts said the sum was “egregious” when he agreed to retire in October 2011. The following February, Isenberg instead agreed to forego the $100 million payment, as well as any claims he may have had against the oil and gas drilling and exploration company, which has operations in Houston.

Typically, the arrangements are part of a CEO’s employment contract, and they can get complicated, said David Percival, CEO of executive energy talent firm Spencer Ogden, based in London.

How old ARE they?

Ages of the CEO of the largest oil and gas public companies in Houston, 60 or older.